In the text mode help:
Selecting Grow to fill disk allows that partition
to increase or decrease in size as files are added
and/or removed from your system. Selecting this
option for partitions, such as the / (root)
partition, which will have data constantly written
to it is always a good idea.
This is completely bogus - the option actually causes free space on the disk
to be (evenly?) distributed among all partitions which have this option selected.
So if you select it for a single partition, it will use up all remaining free space.
It has NO EFFECT whatsoever to the post-install behavior of the system.
The description might possibly lead users to false sense that the partitioning
layout doesn't matter much, because size of the partitions will be
automatically adjusted when needed.